Add Python3 xena unit tests

This is an automatically generated patch to ensure unit testing
is in place for all the of the tested runtimes for xena.

See also the PTI in governance [1].

[1]: https://governance.openstack.org/tc/reference/project-testing-interface.html

Change-Id: Ia6bc6d42aac4aaa35717b9b01a063362bab4c355

zuul.d/project.yaml

@@ -3,7 +3,7 @@
       - publish-openstack-docs-pti
       - release-notes-jobs-python3
       - check-requirements
-      - openstack-python3-wallaby-jobs-neutron
+      - openstack-python3-xena-jobs-neutron
       - openstack-lower-constraints-jobs-neutron
     check:
       jobs: